Method and system for spinning with a rotary balloon-checking device

ABSTRACT

An invention for spinning with a balloon controlled by a checking device is disclosed. The invention is set in rotation by a spindle by means of a yarn, comprising the arrangement of a segment of free yarn constituting a balloon having a controlled and constant height and diameter of base and also comprising the arrangement of a guided segment of yarn downstream of the segment constituting the balloon. Also, the invention is for spinning with a rotary balloon-checking device, comprising a rotary checking device positioned about a yarn package and a tube and having a rotatably supported upper portion and a lower portion performing the function of distributing the yarn on the yarn package, wherein the checking device is open at its upper end and has a pre-determined diameter to contact the yarn.

This invention concerns a method for spinning with a controlled balloonand also a system for spinning with a rotary balloon-checking devicewhich carries out the method.

The spinning system of the invention is suitable to spin and twistfibres of any material, whether of a staple length for wool or a staplelength for cotton;

The invention is especially advantageous for yarns of a medium-fine andfine count and for yarns of materials which are mechanically lessresistant or are more sensitive to the heating action of the ring intraditional systems.

In general, the invention is especially advantageous in all cases wherethe yarn is very subject to breakage, such as, for instance, in spinningpure wool, or is very subject to damage caused by heat, as in thespinning of manmade fibres, for example.

The known art includes many systems for spinning fibres with insertionof a real twist, such as a ring spinning system, for instance.

Good spinning of such a type should obtain a qualitatively sound yarn ata satisfactory speed of output and with yarn packages of a good weightsuitably packaged for the subsequent processes.

To obtain this purpose the spinning system should make possible thefollowing:

the selection of the optimum value of tension during spinning, namelythe tension on the thread leaving the drafting unit until it has beenstrengthened by the twisting; this means in practice the ability topredetermine a value of tension which is limited and as uniform aspossible throughout the whole formation of the yarn package;

the adaptation of such tension to the requirements proper to thewinding, independently of the pre-selected spinning tension, so as toform a yarn package of an optimum density; in practice a higher tensionis required on the yarn at the moment it is wound on the yarn package,which otherwise would be too soft;

the ability to keep optimum spinning and winding tensions even at highspeeds and with yarn packages of good sizes.

As regards the above the various known spinning systems with theinsertion of a real twist entail various limits.

Ring spinning machines involve the drawback of giving rise to a balloonof large dimensions which depend on the diameter and height of the yarnpackage.

The outcome is a high tension on the yarn in the spinning zone, suchtension being strictly linked to the speed of rotation of the spindle.

Moreover, such tension is not uniform since it is affected by thedisturbances undergone by the traveller moving on the ring; suchdisturbances cause in the yarn very high frequency vibrations whichincrease considerably the likelihood of breakages, especially in thecase of weak, fine yarns.

In such systems the balloon is checked with stationary rings on whichthe rotating yarn slides, thus leading to a possibility of damage to theyarn and an arresting action on the re-ascent of the twist towards thedrafting unit.

Other elements being equal, the tension on the yarn in correspondencewith a spinning balloon depends on the maximum radial dimension of theballoon.

The restriction of a large balloon, independently of the restrictionmeans, does not reduce the tension on the yarn but does form an obstacleto the re-ascent of the twist.

Moreover, the traveller has a well determined limit of speed beyondwhich it burns; in any event it always tends to heat up and therefore todamage yarns consisting of materials sensitive to heat, such as yarns ofmanmade fibres, for instance.

In such a system the winding tension is strictly linked to the spinningtension since the whole system is in a dynamic equilibrium tied to thepre-selected working conditions. Such system therefore entails obviousspeed limits which can only be raised by sacrificing the dimensions ofthe yarn package.

In classic bell-type spinning machines, whether the bell be stationaryor rotary, the balloon always possesses large dimensions linked to thedimensions of the package, whether that package be a bobbin or a cop ofyarn.

In this case the balloon is controlled by making the yarn slide on thelower edge or outer surface of the bell.

To maintain contact with the yarn, the bell tends to enlarge theballoon, with a consequent high spinning tension.

The bells in such cases possess considerable dimensions, which are suchas to contain at first the whole tube or support of the yarn package. Inview of their weight the bells are generally stationary or are set inrotation mechanically.

Since the rotations of the yarn and bell are not synchronized in suchsystems, there is always sliding due to rotation as a consequence.

The winding tension on the package is always tied to the spinningtension and depends on the working conditions applied.

In other spinning systems providing for rigid rotary elements such asbells or the like, the yarn is guided along its whole path by the threadguide until it is wound on the yarn package.

Such known systems entail complete elimination of the balloon, andtherefore there is no exploitation of the ability of the balloon tocushion, by means of its capability of being deformed, the instantaneousand/or periodical fluctuations in tensions which take place in the yarnas its winding diameter varies or as a result of unavoidabledisturbances during working.

Such an embodiment is described, for instance, in patent DE-A1-3.400.327in the name of Zinser. In this patent the rotary bell has of necessityto contain the whole tube at the start and also is supported as acantilever so as to enable the yarn to be wound in coils on the outersurface of the bell itself. As a result, the bell has a considerablelengthwise extent and therefore a considerable mass.

This feature entails a great inertia in respect of rotation of the bell,and this inertia has an unfavourable effect on the start-up and stoppingsteps and on the ability of the system to adapt itself to the periodicaland instantaneous changes in speed which occur during formation of ayarn package.

Moreover, the number of coils formed by the yarn on the surface of thedevice, such number being self-regulated according to the workingconditions, is smallest at the time when the winding is taking place onthe smallest diameter, that is, on the tube. When winding is takingplace on the tube, this time coincides with the maximum value of tensionon the yarn being wound, precisely when the segment of yarn wound incoils is at its minimum length and therefore possesses a minimum abilityto cushion the tensions.

The result is a high value of instantaneous corresponding tension, whichtravels back along the yarn to the drafting unit.

The known art provides also for such balloon-checking devices to bepowered, and an example of this is given in the cited DE-A1-3.400.327,the purpose being to surpass the limits of sliding capacity and inertiaproper to idling devices which are drawn by the yarn, espeically in thecase of fine yarns.

Such systems still do not provide the possibility of programmingseparately the spinning tension and winding tension.

In conclusion, in the present state of the art no spinning system isknown which offers all the requirements for optimum spinning as saidabove at one and the same time.

The purpose of this invention is to overcome the drawbacks andshortcomings of the known art by providing a new spinning method whichcan be applied to every type and count of yarn and which enables thespinning performance to be improved as regards the development of thespinning and an increase in speed.

The new system is different in that it does not eliminate the balloonbut reduces its radial dimension by means of a rigid checking device toa value smaller than that of the diameter of the yarn package, the rigidchecking device rotating in synchronization with the yarn about the yarnpackage. Such checking device acts also as a means to wind the yarn onthe yarn package by means of its lower portion shaped as a truncatedcone.

The new spinning system enables a yarn package of normal dimensions tobe obtained with the formation of a balloon having a reduced diameterand height, the balloon being checked and controlled at least partiallyby a rigid, rotary checking device that rotates in synchronization withthe yarn about the yarn package being formed.

Downstream of the zone of the balloon, which stretches between thethread eye and the upper end of the rotary balloon-checking device, thisdevice acts as a guide for the yarn and as a means to wind the yarn onthe yarn package.

There will therefore be a first segment of yarn between the draftingunit and the thread eye as in the known art, a second segment of yarn ofa desired length which constitutes a balloon of limited dimensionscontrolled as regards its geometric parameters (height and diameter atits base), a further segment in which the yarn is guided and controlledin a desired manner until it leaves the device, and a free terminalsegment which is wound onto the yarn package and transmits from thespindle to the checking device of the invention the force to set suchdevice in rotation.

In this new system, starting with the winding tension, it is possible topre-arrange the reduction of such tension to a desired reduced value onthe basis of the balloon coinciding with the spinning tension; this canbe obtained by selecting a suitable winding arc on the outer surface ofthe lower truncated-cone portion of the rotary checking device.

In a preferred embodiment the rotary balloon-checking device of theinvention consists of a hollow cylinder with a truncated-cone base whichis set in rotation by the spindle by means of the yarn. Such cylindertherefore performs at one and the same time the functions of an elementto retard the winding of the yarn on the yarn package and of a rotaryballoon-checking device.

The device is supported by a rail and is free to rotate; it also windsthe conical portion of the yarn package being formed and part of thetube but leaves the top of the latter free.

For a given height of the yarn package, therefore, the device has anextent considerably reduced in a lengthwise direction.

The device therefore has a limited mass and inertia.

The yarn coming from the drafting unit of the spinning machine passesthrough the thread eye in a conventional manner and then forms a freesegment in which the controlled balloon is formed during working; next,the yarn enters the top of the device in correspondence with apre-determined diameter.

In the new system, so far as possible the checking device does not keepclose to the tube and to the yarn package being formed, thus minimizingthe aerodynamic resistance of the system, but the diameter of the upperportion of the checking device is selected in such a way that theballoon will possess a dimension such as to ensure a desired value oftension in the spinning and to prevent sliding of the yarn on the edgeof the tube during start-up.

This diameter corresponds to the diameter of the base of the balloon andis established to suit the type of yarn so as to ensure for the balloonthe condition of stability needed for good spinning together with alimited value of tension.

The yarn then is guided into the cylindrical portion of the checkingdevice and may be simply guided onto its surface or be guided by a smallpipe or conduit.

The yarn thus emerges onto the outer surface of the device below thesupport zone of the device itself or directly at the lower edge of thedevice and is wound onto the yarn package being formed. The yarn maypossibly slide for a certain distance on the outer surface of thetruncated-cone base and on the edge of the rotary balloon-checkingdevice. The conical portion of the device acts as a distributor for theyarn.

The yarn may be left wholly free to move along the edge of thedistributor portion, or its freedom may be restricted to a partial arcor be limited to a definite point, depending on the specific resultrequired.

For a given base diameter of the balloon there is a limit of height forthe same; with a height greater than this limit the balloon collapses.

The nearer this limit of height is approached, the more enlargedradially is the configuration of the balloon with an increased tensionon the yarn, the configuration becoming less and less able to keep itsstability against momentary spinning disturbances.

It follows that in most cases a tube used to form a yarn package cannotbe limited in height to the inside of a free balloon having a small basedimension.

The new spinning system limits with its upper portion the balloon in theradial direction and at the same time lengthens it lengthwise.

An advantage of the new system is its simultaneous performance of threeactions:

radial reduction of the base of the balloon,

limitation of the height of the balloon, and

the ability to pre-determine the spinning tension by choosing a givenarc of winding on the surface of the lower truncated-cone portionindependently of the radial reduction of the balloon.

We list below further advantages of the invention:

the invention enables the speed of output to be increased and, at thesame time, the spinning conditions to be improved,

the balloon is limited and, as a result, so also is the level of tensionin the yarn leaving the drafting unit; this is due to the fact that therotary checking device has radial dimensions which are smaller than thediameter of the yarn package,

it is possible to regulate the winding tension by means of a brake in aknown manner and to pre-set the reduction of that tension to an optimumreduced value in the spinning zone, where the yarn is still beingstrengthened by being twisted; this is brought about by selecting thelength of the portion of the device on which the yarn is to slide,

such portion for the sliding of the yarn according to the invention canbe pre-set wholly or partially; for such partial pre-setting a limitedand pre-set field of freedom of the yarn can be provided along the edgeof the device,

the geometric dimensions, that is, the base and height of the balloon,are selected so as to provide an optimum tension in the spinningconditions for the whole envisaged range of yarns; in fact, with aconstant geometry of the balloon the spinning tension will varyautomatically as the count varies, and will be lower for fine yarns andprogressively greater for the thicker yarns; such self-regulation iswell suited to the spinning requirements,

the tension is more uniform, especially as regards oscillations for ashort period, in view of the cushioning capability of the balloon andthe lack of a traveller,

the control of the spinning tension performed by means of the inventionin the segment between the point where the yarn begins receiving a twistand the point where the yarn, still being consolidated, leaves thedrafting unit, ensures an even and modest value of tension; as a result,the spinning is excellent,

the reduced tension means also an easier re-ascent of the twist sincethe yarn-guide loop constitutes a lesser obstacle as an outcome of thelesser thrust of the yarn on the walls of the loop,

there is a pre-determined or only partially free winding of the yarn onthe truncated-cone distributor portion of the device; this obviates thepresence of several coils at the moment of least tension and vice versaat the time of variation in the winding diameter; such variation ofcoils in the known art entails an accentuation of the variation intension experienced when the winding diameter varies,

the spinning system entails a fixed path for the yarn from the draftingunit to the yarn package if the rail bearing the checking device isstationary; if such rail can move and the rail bearing the spindles isstationary, the fixed path will run from the thread eye to the yarnpackage; as a result, in both cases the whole formation of the yarnpackage will take place with a constant balloon,

the dimensions, weight and inertia of the rotary balloonchecking deviceof the invention are smaller than the corresponding parameters of knownbell systems if the dimensions of the yarn package are the same in bothcases, and therefore acceleration is facilitated during start-up and thesystem follows more easily the variations in revolutions of thedistributor portion of the device in winding the variable diameter ofthe yarn package, thus preventing the occurrence of high points oftension,

in view of the limited diameter of the cylindrical portion of thedevice, the device itself is supported at diameters smaller than that ofthe yarn package and therefore in advantageous conditions for reaching agreat sliding capability, which is essential for the spinning of fineyarns in particular,

the system does not contain points where the yarn will become hot, anddamage will therefore be obviated, especially with manmade fibres.

The invention is therefore obtained with a method for spinning with aballoon controlled by a rotary checking device, in which method the yarncomprises a first free segment between a drafting unit and a thread eyeand a terminal free segment between the checking device and a yarnpackage, the checking device being set in rotation by a spindle by meansof the yarn, the method being characterized in that it comprises:

the arrangement of a segment of free yarn constituting a balloon havinga controlled and constant height and diameter of base downstream of suchfirst free segment of yarn, and

the arrangement of a guided segment of yarn downstream of the segmentconstituting the balloon and upstream of the terminal free segment ofyarn.

The invention is also embodied with a system for spinning with a rotaryballoon-checking device, the system comprising a rotary balloon-checkingdevice positioned about a package of yarn and a tube and having arotatably supported upper portion and a lower portion performing thefunction of distributing the yarn on the yarn package, the system beingcharacterized in that the checking device is open at its upper end andhas a pre-determined diameter to contact the yarn.

We shall now describe, as a non-restrictive example, a set of preferredembodiments of the invention with the help of the attached figures, inwhich:

FIG. 1 shows an embodiment of the invention;

FIG. 2a through 2d show variants of the embodiment of FIG. 1;

FIGS. 3 through 6b show possible variants of the checking device of theinvention;

FIG. 7a through 7f show the various steps in the formation of a yarnpackage with a constant balloon;

FIGS. 8a through 8e give a diagrammatic comparison of a traditionalballoon and the balloon of the invention;

FIGS. 9a and 9b show further variants.

In the figures the same parts or parts having the same functions bearthe same reference numbers.

In FIG. 1 a spinning system 10 is applied to a spindle 11, which in thiscase is driven by an independent motor 12 fitted to a rail 13, which ismoved with a reciprocating vertical motion 42 shown by an arrow, so asto form a package of yarn according to known methods. A yarn package 14is shown during its formation on a tube 15.

A balloon-checking device 16, which consists of an upper cylindricalportion 27 and a lower truncated-cone or distributor portion 28,surrounds the yarn package being formed and lets the top of the tube 15protrude upwards.

The cylindrical portion 27 is upheld by a support 17 with a bearing, thesupport being integrally fixed to a rail 19 of a spinning machine, suchrail being stationary in this example.

A brake 18, of a magnetic type for instance, serves to graduate thewinding tension in a known manner.

A yarn 22 coming from a drafting unit 20 forms a first segment 23reaching a thread eye 21; a second segment of yarn 24 between the threadeye 21 and the top of the balloon-checking device 16 forms a balloon, ascan be seen in FIG. 1.

This balloon has a controlled geometry since the values of the diameterof its base D (corresponding here to the inner diameter of thecylindrical portion 27) and of its height H (corresponding to thedistance between the thread eye and the top of the checking device 16)are pre-set.

The height H will preferably be adjustable, for instance, by changingthe height of the thread eye 21 with an adjustment means 38. Thediameter D will be chosen beforehand to suit the spinning conditions andthe range of yarns to be spun.

As can be seen in FIG. 1, the diameter D will be smaller than thediameter of the yarn package 14.

After the yarn has entered the checking device, it forms a segment 25which is controlled until it is wound on the yarn package 14.

In the embodiment shown in FIG. 1 this segment 25 comprises a firstportion 125 inside the checking device 16; it then emerges from thedevice 16 through an outlet hole 26, passes along the surface of thedistributor portion 28 and then enters a lead-in 29 which determines thelength of yarn between the outlet hole 26 and the lower edge of thedistributor portion 28. The yarn is then wound onto the yarn package 14.

The lead-in 29 causes the yarn 22 to be engaged automatically atstart-up; in this way the length of the portion 225 of yarn between theoutlet hole 26 and the lead-in 29 remains constant.

FIGS. 2a through 2d show variants of the invention as applied to aspindle 11 which in this case is driven by a pulley 30 coooperating in aknown manner with a belt, which is not shown. The spindle 11 is fittedto a rail 13 which is stationary in this example.

Instead, the checking device 16 is fitted by means of the support 17 toa rail 19 which here is able to move to form the yarn package 14, as isshown by arrows in the figures. This method of movement is also known.

It should be noted that in this way the length of the segment 23 of yarnbetween the drafting unit 20 and the thread eye 21 is varied, whereasthe lengths of the segments 24 and 25 of yarn are not varied. Thus, thegeometry of the balloon remains constant in this case too since the rail19 supports the thread eye 21 too, as is shown in FIG. 2a.

It is possible to arrange also for an embodiment in which both the rails13-19 are able to move. For instance, a reciprocating drawing motionwill be imparted to the rail 19, whereas a motion of one-directionallowering will be imparted to the rail 13 at short intervals, as is knownin the prior art.

To doff yarn packages and don empty tubes, it will be possible to carryout a relative movement as between the rails 13 and 19, for instance bylowering the rail 13 fully and rotating or traversing it so as to assistthe doffing of a yarn package or the donning of a tube, or by performinganother like movement.

Moreover, the rail 19 supporting the checking device 16 may be capableof being displaced transversely to a position out of alignment with thespindles.

In the embodiment of FIG. 2a the segment 24 of yarn forming the balloonends at an inlet hole 31. In this case the diameter D of the base of theballoon coincides substantially, therefore, with the outer diameter ofthe cylindrical portion 27 of the checking device since it isgeometrically determined.

The yarn 22 enters the checking device 16 through the inlet hole 31 andforms the first guided portion 125 of the segment 25 of yarn.

The yarn 22 then emerges from the outlet hole 26, slides on the surfaceof the distributor portion 28 of the checking device (portion 225 ofyarn) and enters a winding hole 32.

FIG. 2a shows two winding holes 32 diametrically opposite to each other,but it is to be understood that there can be a plurality of windingholes 32 (or of lead-ins in FIG. 1) at separate positions so as to varythe length of the portion 225 of yarn as required. Likewise, there maybe a plurality of outlet 26 and inlet 31 holes.

In this way it is possible to alter the percentage of tension dischargedby friction between the yarn 22 and the checking device 16.

It should be noted that in the embodiment of FIG. 2a the yarn forms twoelbows at the inlet and outlet holes 31-26, and a part of the tensionwill therefore be discharged at those elbows.

FIG. 2b shows a variant in which the inlet hole 31 for the yarn to enterthe device is machined in a ring 41 within the cylindrical portion ofthe device and at the upper edge of the device. In this embodiment theyarn enters the device at a tangent to the inner wall, as in theembodiment of FIG. 1, but in this case the yarn is kept distant from thetube at start-up during the transient stage of start-up when the balloonstill does not exist.

FIG. 2c contains a variant in which the yarn is guided, outside theupper portion of the device, along the segment 325 of yarn between theinlet hole 31 and outlet hole 26. In this case the segment 125 of yarnwithin the device develops along the whole height of the support.

FIG. 2d shows a variant in which the yarn is guided outside the sidewallof the upper portion of the device by means of a conduit 34 in which theyarn enters at the base of the balloon and leaves along the surface ofthe lower portion. This embodiment facilitates the threading of the yarnand the provision of a ceramic conduit particularly resistant to thewear caused by the yarn.

FIG. 3 shows a variant in which the distributor portion 28 of thechecking device comprises a lead-in 29 as in FIG. 1, but a plurality ofoutlet holes 26 have been provided to vary the length of the portion 225of yarn between the outlet hole 26 momentarily employed and the lead-in29.

FIG. 4 shows a variant of the checking device that provides an elongatedlead-in 33 in which the yarn 22 has a partial freedom of movement, asshown by arrows. Such partial freedom of movement may cushion anyinstantaneous variations in tension, and this cushioning effect may beadded to the cushioning effect of the balloon or may well take up anyvariations in tension of a certain frequency, whereas the effect of theballoon may be greatest with regard to variations of a differentfrequency.

FIG. 4 shows diagrammatically a plurality of outlet holes 26 arrangedalong a generating line of the cylindrical portion 27 of the checkingdevice. If the yarn 22 is caused to emerge from one or another of suchholes, the length of the portion 225 of yarn between that outlet holeand the lower edge of the distributor portion 28 of the checking devicewill be varied.

The arc of winding of the portion 225 of yarn can also be pre-set toconsist of one or more coils about the distributor portion 28 of thedevice by pre-arranging the yarn in the outlet hole 26 or lead-in 29 orinlet hole 32 suitable for the purpose.

The conformations of the holes or lead-ins 29, 31, 32, 33 shown in thefigures are given merely as examples since the conformation will beselected in each case to optimize the running of the yarn.

Likewise, the upper and lower edges of the checking device will beconformed (for instance, rounded) so as to avoid damaging the yarn.

FIG. 5 shows another variant, in which the portion 125 of the yarn 22 isguided in a conduit 34 consisting here of a small pipe solidly fixed tothe wall of the cylindrical portion 27 of the checking device. Thissmall pipe 34 opens out into the outlet hole 26. This embodiment isespecially useful for assisting the threading of the yarn.

In FIG. 5 too the portion 225 of yarn is not limited to a preferredposition on the lower edge of the distributor portion 28 of the checkingdevice but is free to move without any particular constraints apart fromthose imposed by equilibrium between the momentary traction applied tothe yarn and the resistance to the motion of the balloon-checking device16.

Instead, FIGS. 6a and 6b show an embodiment in which several small pipes34 of different lengths extend along the whole length of the checkingdevice 16. The lower end of each small pipe opens out at the edge of thedistributor portion 28 of the checking device. The segment 25 of yarn istherefore guided completely within the small pipe 34. In this case thepre-determination of the winding arc is obtained by selecting the mostsuitable pipe 34.

It can be understood at once that all the intermediate situationsbetween that of FIG. 5 and that of FIGS. 6a and 6b can be provided, thatis to say, the small pipe 34 may end at any lengthwise position in thedevice, for instance at an outlet hole 26 located as required along agenerating line of the distributor portion 28 of the device.

Moreover, instead of the conduit or small pipe 34 there may be a seriesof conduits or channels machined in the body of the checking device andhaving a development along a generating line or possibly a spiraldevelopment.

FIGS. 9a and 9b respectively show a section and a front view of avariant of the system to anchor the yarn to the surface of thedistributor portion with a view to the predetermination of the windingarc. In this case the yarn leaving the outlet hole 26 is taken to a holeor guide 29, which is machined in a ring protruding from the outersurface and located at a certain distance from the edge of the device;the yarn is wound thereafter onto the yarn package.

In this embodiment the anchorage point 29 of the yarn is positioned at acertain distance from the edge of the device and therefore provides agiven freedom of movement of the yarn on such edge with regard to thevarious winding steps.

Moreover, this embodiment enables optimum geometrics and surfacetreatments to be applied to the edge of the checking device.

It is to be understood that there may be a plurality of outlet holes 26or anchorage holes 29 so as to obtain the desired ability to select thewinding arc.

FIGS. 7a through 7f show the formation of a complete yarn pachage with aconstant balloon. In this example the device 16 is stationary whereasthe spindle 11 can move, as in FIG. 1, but it is clear that the samemethod can be applied to the case of FIG. 2a where the spindle rail 13is stationary and the rail 19 of the device can move, or to any othercase.

It should be noted that in all the steps of formation of the bobbin(7a-7b) and with all the winding diameters momentarily occurring theballoon keeps constant its basic geometric parameters D and H.

It should be noted from FIG. 7a that the lower limit of the value of thediameter D is the diameter of the tube 15.

FIGS. 8a, 8b and 8c give a comparison of the balloon obtained with astationary checking ring of the traditional type and the balloonobtained with the rotary checking device of this invention with regardto the yarn package to be wound.

FIG. 8b shows a spinning ring 35 with a small ring 36. A traditionalchecking means 37 consists in this case of a ring having a diameter thesame as that of the spinning ring 35. Instead, FIG. 8c gives a diagramof the checking device 16 of FIG. 1. It is possible to see that, if theyarn package 14 has an equal diameter, the balloon remains in the upperzone alone and has reduced dimensions. This enables many advantages tobe obtained which have already been cited in the introductory part ofthe description.

FIG. 8d shows a variant of the device 16 in which the rotary checkingdevice cooperates with a traditional stationary checking device, whetherit be a ring or another device, to control the balloon. Such anembodiment might be employed in the case of an especially high tube orwhere it is essential to overcome problems of overall bulk or lightweight in particular applications of the invention.

FIG. 8e shows an embodiment kept to a minimum of height and especiallysuitable for tubes of a limited height, such as those employed for veryfine yarns or yarns having special requirements regarding their abilityto be unwound.

We have described here a set of preferred embodiments of the invention,but many variants are possible without departing thereby from the scopeof the invention.

Thus the lengths and reciprocal proportions of the yarn segments 23 and24 and yarn portions 125, 225 and 325 can be varied, and any requiredplurality of outlets 26 or inlets 31 or outlets 32 or lead-ins 29 orrecessed portions 33 can be produced, which in turn can coexist in anydesired arrangement in one and the same checking device 16.

The checking device 16 itself may have an overall tapered or possiblycurved shape, for instance with a cigar-point shaped portion 28 or avariously radiused form.

These and yet other variants are possible without departing thereby fromthe scope and spirit of this invention.

We claim:
 1. A method for spinning with a balloon which comprises a yarn controlled by a rotary checking device, wherein the yarn comprises a first free segment between a drafting unit and a thread eye, and a terminal free segment between the checking device and a yarn package, wherein the checking device is set in rotation by a spindle by means of the yarn, the method comrising the steps of:a. arranging a segment of free yarn to form a balloon comprising a portion of the yarn and having a controlled and constant height and diameter of a base downstream of said first free segment of yarn, and b. arranging a guided segment of yarn downstream of the segment constituting the balloon which comprises a portion of the yarn and upstream of the terminal free segment of the yarn.
 2. The method as claimed in claim 1, in which the height of the balloon is substantially the height between the thread eye and the point of entry of the yarn into the checking device.
 3. The method as claimed in claim 1, in which the diameter of the base of the balloon is substantially the same as the diameter of contact between the balloon and the top of the checking device, and such diameter is less than or equal to the diameter of the yarn package.
 4. The method as claimed in claim 3, further comprising the step of adjusting the height of the balloon.
 5. The method as claimed in claim 4, in which the guided segment of yarn comprises at least one portion within the checking device.
 6. The method as claimed in claim 5, in which the guided segment of yarn comprises at least one portion outside the checking device.
 7. The method as claimed in claim 6, in which the guided segment of yarn has a length which can be preset.
 8. The method as claimed in claim 7, in which the guided segment of yarn has a constant length.
 9. The method as claimed in claim 7, in which the guided segment of yarn has a length which may vary in a controlled range.
 10. The method as claimed in claim 6, in which the guided segment of yarn has a freely variable length.
 11. A system for spinning a yarn package about a tube and controlling the dimensions of the balloon thereby generated with a single mechanism, comprising:a rotary yarn-balloon-checking device positioned about the yarn package and the tube; said checking device having a rotatably supported upper portion and a lower distributor portion for distributing the yarn on the yarn package, wherein said checking device is open and unobstructed at its upper end for allowing the formation of the balloon which comprises a portion of the yarn and has a pre-determined diameter to contact the yarn, the diameter of the upper end of the checking device being equal to or less than the diameter of the yarn package.
 12. The system as claimed in claim 11, further comprising a thread eye for guiding the yarn, the distance between said thread eye and the top of said checking device being adjustable so as to control the height of the balloon.
 13. The system as claimed in claim 12, in which said checking device has a length substantially smaller than that of the tube.
 14. The system as claimed in claim 13, in which said checking device is freely rotatably supported by a support at the lower end of said upper supported portion adjacent said distributor portion.
 15. The system as claimed in claim 14, in which said checking device comprises at least one inlet hole for the yarn in a diametral position.
 16. The system as claimed in claim 15, in which said checking device comprises at least one outlet hole for the yarn at a desired position below said support.
 17. The system as claimed in claim 16, in which said checking device comprises at least one lead-in on the lower edge of said distributor portion.
 18. The system as claimed in claim 17, in which said checking device comprises at least one passage for winding the yarn in the vicinity of said lower edge of the distributor portion.
 19. The system as claimed in claim 18, in which said checking device comprises at least one recessed portion on the lower edge of said distributor portion.
 20. The system as claimed in claim 19, in which said checking device comprises a guide conduit along at least part of the lengthwise extent of said checking device 